Circularly Polarized Dispersive Alfvén Wave In Solar Wind Turbulence
Previously Published Material: No, the present article is to be submitted in a scientific journal soon.
Abstract ID#: 34756
The physical properties of solar wind turbulence and its evolution have been an intense topic of exploration for decades. The inertial range of Solar wind turbulence can be described by a magnetohydrodynamic model. The dispersive range of the solar wind turbulence likely consists of several kinds of waves. The obliquely propagating waves, e.g., the kinetic Alfvén wave and whistler wave, are considered to be an important factor in the solar wind turbulence. On the other hand, parallel propagating right(R) and left(L) circularly polarized Alfvén/ ion cyclotron wave in the framework of Hall MHD are also thought to be essential ingredients of the solar wind turbulence. Recently, He et.al[1] have used the magnetic field data from the STEREO spacecraft to calculate the magnetic helicities in the solar wind turbulence. Their analysis indicates the possible existence of Alfvén -cyclotron waves and their coexistence with the right handed polarized fluctuations (kinetic Alfvén waves or whistler waves). In the present article we intend to study the temporal evolution of right and left circularly polarized dispersive Alfvén wave (DAW) and their role in the solar wind turbulence. Dispersion is considered on account of the finite frequency (frequency comparable to ion gyro frequency) of the pump wave. The individual DAW dynamics of two modes in the presence of the density fluctuations (ion acoustic/magnetosonic) is obtained and simulated numerically. We have then studied the transient evolution of DAW when transverse density perturbations are present in the background. The power spectrum is investigated which shows a steepening for scales larger than the proton inertial length. This is consistent with the recent work by Meyrand et.al[2]. The observations in the solar wind also indicate that L and R modes coexist uptil the pump wave frequency remains less than or comparable to the ion cyclotron frequency[1].
References :
[1] J. He, E. Marsch, C. Tu, S. Yao and H. Tian, Astrophysical Journal, 731, 85 (2011)
[2] R. Meyrand and S. Galtier, Phys. Rev.Lett., 109, 194501(2012)